Abstract

In this research, FeCo alloy magnetic nanofluids were prepared by reducing iron(III)
chloride hexahydrate and cobalt(II) sulfate heptahydrate with sodium borohydride in
a water/CTAB/hexanol reverse micelle system for application in magnetic hyperthermia
treatment. X-ray diffraction, electron microscopy, selected area electron diffraction,
and energy-dispersive analysis indicate the formation of bcc-structured iron-cobalt
alloy. Magnetic property assessment of nanoparticles reveals that some samples are
single-domain superparamagnetic, while others are single- or multi-domain ferromagnetic.
The stability of the magnetic fluids was achieved by using a CTAB/1-butanol surfactant
bilayer. Results of Gouy magnetic susceptibility balance experiments indicate good
stability of FeCo nanoparticles even after dilution. The inductive properties of corresponding
magnetic fluids including temperature rise and specific absorption rate were determined.
Results show that with increasing of the nanoparticle size in the single-domain size
regime, the generated heat increases, indicating the significant effect of the hysteresis
loss. Finally, the central parameter controlling the specific absorption rate of nanoparticles
was introduced, the experimental results were compared with those of the Stoner-Wohlfarth
model and linear response theory, and the best sample for magnetic hyperthermia treatment
was specified.